Applications of the converter include, but are not limited to, stepping up a very low voltage from an energy harvesting device to a useful supply voltage.
An energy harvesting device is a device that generates electrical energy from an external or environmental source. Examples include radio frequency (RF) energy harvesters that collect radio frequency energy from ambient or dedicated sources, and a micro-thermoelectric generator that collects heat. A useful supply voltage is a voltage that is adequate to power a specific electronic circuit or device that is coupled (wired or wirelessly) with the energy harvesting device. The magnitude of the supply voltage that is useful will depend on the specific device in question.
One example application area is in the field of body sensor nodes (BSNs). These promise to provide significant benefits to the healthcare domain by enabling continuous monitoring, actuation, and logging of patient bio-signal data, which can help medical personnel to diagnose, prevent, and respond to various illnesses such as diabetes, asthma, and heart attacks. Though they show great potential, BSNs have many technical challenges that impede their widespread adoption including node operating lifetime, small form factor for wearability, and affordable cost. Conventional wireless sensors use batteries, limiting node lifetime and reducing user compliance due to the requirement for charging or replacing batteries.
Other forms of wearable technology promise significant benefits but are held back by similar technical challenges.
A DC-DC charge pump is required in order to step up an energy harvesting device's output voltage. However existing converters require mechanical start-up circuits or pre-charged batteries in order to start-up at very low voltages.